David Galloway

If you don't want to give out your real email address to register for a site and don't want to go through the hassle of creating a spam email address, just point your browser to Guerrilla Mail; upon loading the page you'll have an automatically assigned email address from the domain sharklasers.com that is good for one hour.

The beauty of Guerrilla Mail is that when you visit the URL you're automatically logged into the inbox of your temporary email address; just don't navigate away until you're finished with the email address. There are buttons to extend the address by an hour, copy your temporary email address to your clipboard, and to forget the address. I imagine that last option would be great to use after firing off a scathing anonymous email—when the recipient tries to respond they learn that the address no longer exists.